Percutaneous needle guide and methods of use

ABSTRACT

An indicator element of a percutaneous needle guide for a medical scanning device includes a pointer for pointing to a percutaneous needle entry site on an epidermis of a body, when the guide is attached to the device and the device is positioned over the epidermis for scanning. A user may orient and insert a needle into the entry site according to the direction of the pointer, by just viewing the pointer, without the needle being constrained by the pointer. The guide may include an adjustment mechanism for moving the indicator element with respect to the device, when the guide is attached to the device; the adjustment mechanism moves the indicator element, without changing an orientation of the pointer, in a direction approximately parallel to a plane that is approximately tangent with an apex of the device transducer surface and approximately perpendicular to a longitudinal axis of the device.

RELATED APPLICATION

This patent application is a divisional of U.S. patent application Ser.No. 11/757,516, filed Jun. 4, 2007, now allowed, the entire disclosureof which is expressly incorporated herein by reference.

TECHNICAL FIELD

The present invention pertains to gaining percutaneous access to asubcutaneous target located by a non-invasive medical scanning deviceand more particularly to guiding insertion of a percutaneous needlethrough an epidermis of a body to gain the access.

BACKGROUND

Various designs of percutaneous needle guides for attachment tonon-invasive medical scanning devices, for example, hand-held ultrasoundtransducer probes, are known in the art. These guides may be used todirect a percutaneous needle, for example, a biopsy needle, to a needleentry site, which is located alongside the scanning device on anepidermis of a scanned body, and which corresponds to a subcutaneoustarget located by the device. In order to direct the needle, theseguides include a constraining feature through which the needle must bepassed. Many of these guides further include means to adjust an angularorientation of the constraining feature, according to a measured depthof the located target, so that the needle inserted therein is directedto the insertion site at an angle that allows the inserted needle tointersect with the subcutaneous target.

Guides which only provide for an angular adjustment of the constrainingfeature, in order to re-direct the trajectory of the inserted needle, donot take into account situations when a particular angular orientationof the inserted needle is important for the needle to pass through thelocated target and gain access to a site beyond the target. Furthermore,handling of a guide including the aforementioned constraining feature,in conjunction with a proper handling of the scanning device and theneedle, can increase a number of steps that a physician or clinicianmust take in order to gain percutaneous access to the target or the sitebeyond the target. Additionally, the constraining feature through whichthe needle must be passed in order to be guided by these guides canimpose unnecessary limitations on a physician or clinician who hasdeveloped skills for “free-hand” handling of needles.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIGS. 1A-B are schematics depicting a needle guide attached to a medicalscanning device in a first position and second position, respectively,according to some embodiments of the present invention.

FIG. 1C is a plan view of a needle guide kit, according to someembodiments of the present invention.

FIGS. 2A-B are first and second perspective views of a needle guideattached to a medical scanning device, according to some alternateembodiments of the present invention.

FIG. 2C is an exploded perspective view of the needle guide shown inFIGS. 2A-B, according to some embodiments.

FIG. 3A is a perspective view of a needle guide attached to a medicalscanning device, according to additional embodiments of the presentinvention.

FIG. 3B is a top perspective view of the needle guide shown in FIG. 3A,according to some embodiments.

FIGS. 4A-B are schematics depicting an exemplary, procedure that mayemploy embodiments of the present invention.

FIG. 5A is a schematic depicting percutaneous needle access obtainedaccording to some methods of the present invention.

FIG. 5B is a reproduction of an exemplary ultrasound scan showing asacral foramen.

FIG. 6A is a plan view of a percutaneous access needle.

FIG. 6B is a perspective view of an alternate embodiment of the guideshown in FIGS. 3A-B.

FIG. 7 is a flow chart outlining various methods of the presentinvention.

FIG. 8 is a schematic depicting a fixed needle guide, attached to amedical scanning device, according to further alternate embodiments ofthe present invention.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of skill in the fieldof the invention. Those skilled in the art will recognize that many ofthe examples provided have suitable alternatives that can be utilized.

FIGS. 1A-B are schematics depicting a needle guide 10 attached to amedical scanning device 100, for example, a hand-held ultrasoundtransducer probe, according to some embodiments of the presentinvention. FIGS. 1A-B illustrate device 100 including a transducersurface 101, to which a plane 2 is approximately tangent at an apexthereof, an external sidewall 103 extending away from transducer surface101, a longitudinal axis 4 approximately perpendicular to plane 2, and acord 3 extending from device 100; cord 3 couples the scanning transducerof device 100 to a console (example shown in FIG. 5A), which, forexample, controls the transducer function, processes and stores datacollected by the transducer, and displays the data. Guide 10 is shownincluding an indicator element 11, an adjustment mechanism 15 and ajoining structure 13, which reversibly attaches guide 10 to device 100such that indicator element 11 is laterally offset from transducersurface 101 and external sidewall 103. Joining structure 13 may includea pair of spring loaded mounting brackets that may be press fit aboutexternal sidewall 103 of device 100.

FIGS. 1A-B further illustrate indicator element 11 including a pointer110 being formed as a terminating edge of element 11, and adjustmentmechanism 15 being coupled to joining structure 13 for moving indicatorelement 11, with respect to device 100, in a direction approximatelyparallel to plane 2 without changing an orientation of pointer 110 asdefined by an angle θ. According to the illustrated embodiment, angle θof pointer 110 is predetermined according to an orientation necessaryfor a percutaneous needle to pass through a subcutaneous target T inorder to gain access to an underlying site; according to an exemplaryembodiment, for an application described below, in which thepercutaneous needle must pass through a foramen of a boney structure,angle θ is between approximately 55 degrees and 65 degrees. Withreference to FIGS. 1A-B, it should be appreciated that pointer 110provides guidance for needle insertion without constraining the needle,so that needle handling on the part of a physician or clinician is notunduly restricted or hampered. According to FIG. 1A, when plane 2coincides with an epidermis of a body, and scanning device locatessubcutaneous target T at a depth D1, indicator element 11 is moved, viaadjustment mechanism 15, to locate a terminal end P of pointer 110 at adistance d1 from axis 4 (axis 4 coinciding with target T); distance d1corresponds to an entry site E1 on the epidermis, to which pointer 110points by virtue of angle θ, and which entry site E1 is located adistance x1 from axis 4, so that a trajectory of a needle (shown by adashed line), inserted at E1 per angle θ, passes through target T atdepth D1. According to FIG. 1B, when plane 2 coincides with an epidermisof a body, and scanning device locates subcutaneous target T at a depthD2, indicator element 11 is moved, via adjustment mechanism 15, tolocate terminal end P of pointer 110 at another distance d2 from axis 4;distance d2 corresponds to another entry site E2 on the epidermis, towhich pointer 110 points, and which entry site E2 is located a distancex2 from axis 4, so that a trajectory of a needle (shown by a dashedline), inserted at E2 per angle θ, passes through target T at depth D2.Adjustment mechanism 15 may be any type expanding and collapsingstructure (one example being a telescoping structure) for movingindicator element 11, with respect to device 100, along a directionapproximately parallel to plane 2, without changing angle θ of pointer110; and, according to some preferred embodiments, adjustment mechanism15 is calibrated to move indicator element 11, with respect to device100, in predetermined increments, each increment corresponding to adifferent target depth.

With reference to FIGS. 1A-B, it should be appreciated that each ofdistances x1 and x2 is approximately equal to a tangent of (90°-θ)multiplied by a depth D1, D2, respectively, and that an offset O betweenterminal end P of pointer 110 and plane 2 is accounted for in thepositioning of indicator element 11 at distances d1 and d2, such thatpointer 110 points to entry sites E1 and E2 that are located atdistances x1 and x2. As offset O decreases, for example, by enlargingindicator element 11 so that terminal end P of pointer 110 is movedcloser to plane 2, distances d1 and d2 approach distances x1 and x2,respectively. According to alternate embodiments of the presentinvention, guide 10 is either shifted, with respect to device 100,toward plane 2, in its attachment thereto, or indicating element 11 isenlarged (for example, as shown with a dotted line in FIG. 1B), so thatterminal end P of pointer 110 is approximately tangent with plane 2(touching, or close to touching entry sites E1 and E2); for embodimentssuch as these, offset O is significantly reduced, and distances d1 andd2 become approximately equal to distances x1 and x2, respectively.

It should be noted that a depth of particular subcutaneous targets maynot varying significantly, from body to body (patient to patient), suchthat needle guides, according to alternate embodiments of the presentinvention, need not include an adjustment mechanism, such as mechanism15. FIG. 1C is a plan view of a kit 150 including a plurality of needleguides 151, 152, 153, FIG. 1C illustrates each needle guide 151, 152,and 153 having a fixed position, for corresponding terminal ends P1, P2,and P3 of pointers 110, which are defined by thicknesses t1, t2, t3,respectively. According to the illustrated embodiment, one of guides151, 152 and 153 may be selected and attached to a scanning device, forexample device 100, according to a depth of a target, either foreknownor measured via scanning device 100, that corresponds to the thicknessof the selected guide. According to some preferred embodiments, eachguide 151, 152, 153 is labeled to indicate a target depth correspondingto thickness t1, t2, t3, and labeled to direct an attachment thereof,via joining structure 13, in a proper position along sidewall 103 ofdevice 100 so that each pointer 110 points to the needle entry site thatcorresponds to the depth indicated on the corresponding guide 151, 152,153. Another embodiment of a “fixed” needle guide will be describedbelow, in conjunction with FIG. 8.

Returning to FIGS. 1A-B, a flexible and transparent disposable covering180 is shown surrounding device 100 and attached guide 10. A freshcovering 180 placed about device 100 and guide 10, for each successiveprocedure, protects against contamination between patients when device100 and guide 10 are reused. Because guide 10 includes pointer 110,which can be easily viewed through cover 180, in order to guide apercutaneous needle insertion, and indicator element 11 may be graspedfrom outside cover 180 for adjustment via adjustment mechanism 15, thereis no need to attach guide 10 outside covering 180; however, accordingto some embodiments, joining structure 13 fits about device sidewall 103that is enclosed within covering 180, so that guide 10 may be attachedto device 100 outside covering 180. In either situation, inside oroutside covering 180, a new guide 10 may be used for each successiveprocedure, or a same guide 10 may be sterilized and reused in eachsuccessive procedure. Disposable embodiments of guide 10 may beinexpensively formed, for example, via injection molding, from a plasticsuch as ABS or nylon, while reusable embodiments of guide 10 may beformed from a metal or a plastic, such as an acetal resin (i.e. Delrin®)or a polycarbonate, that can withstand autoclave sterilizationtemperatures.

FIGS. 2A-B are first and second perspective views of another needleguide 20 attached to medical scanning device 100, according to somealternate embodiments of the present invention. FIG. 2A shows device 100positioned with transducer surface 101 against plane 2 in an orientationvery similar to that shown in FIGS. 1A-B. FIGS. 2A-B illustrate needleguide 20 including a two-part joining structure 231, 232 coupled to anindicator element 21, which is in the form of a plate, and joiningstructure parts 231, 232 wrapping around external sidewall 103 of device100 in order to attach guide 20 to device 100 so that indicator element21 is laterally offset from device transducer surface 101 and externalsidewall 103; joining structure parts 231, 232 are shown coupledtogether via interlocking snap-fit features 23. FIGS. 2A-B furtherillustrate indicator element 21 including a first pointer 209, a secondpointer 210 and a third pointer 211, each extending over a length, alongan exposed face of indicator element 21, at a different angle, but eachhaving a common terminal end P20; pointers 209, 210, 211 are shownformed by edges or ledges of increasingly protruding surfaces of theexposed face of element 21, against which a needle may be rested,however pointers 209, 210, 211 may alternately be formed by grooves inthe exposed face or any other type of marking on the exposed face thatmay not provide a support for the needle.

According to the illustrated embodiment, indicator element 21 is coupledto a lateral extension of each of joining structure parts 231 and 232such that an adjustment mechanism including a knob 270 may moveindicator element 21 with respect to device 100, when guide 20 isattached thereto, and with respect to the joining structure. FIG. 2Billustrates indicator element 21 mounted to joining structure part 231via pegs 213 that extend, from a surface of indicator element 21, whichis opposite the exposed face thereof, and through slots 201 of thelateral extension of joining structure part 231; pegs 213 extending inslots 201 maintain a fixed orientation of each pointer 209, 210, 211,while allowing indicator element 21 to be moved toward and away fromdevice 100, in a direction approximately parallel to plane 2, by knob270 of the adjustment mechanism. Thus, the adjustment mechanism may beused to move terminal end P20 of pointers 209, 210, 211 into a positioncorresponding to a measured depth of a subcutaneous target, which hasbeen located by device 100, in order to guide insertion of apercutaneous needle along a proper trajectory to pass through thelocated target, as previously described in conjunction with FIGS. 1A-B.Pointers 209 and 211 on either side of pointer 210 may provide a frameof reference for an acceptable tolerance, for example, approximately ±5to 10 degrees, on an angle of insertion, as defined by pointer 210,required to pass the needle through a particular subcutaneous target, orpointers 209, 210, 211 may provide guides for alternative angles ofentry, each angle of entry appropriate for passage of a needle through adifferent type of subcutaneous target. It should be noted that althoughFIG. 2A shows the three pointers 209, 210, 211, alternate embodiments ofguide 20 may include just one pointer, or any number of pointers.

Referring now to FIG. 2C, which is an exploded perspective view ofneedle guide 20, in conjunction with FIG. 2B, the adjustment mechanismof guide 20 will be described in greater detail. FIGS. 2B-C illustratethe adjustment mechanism including knob 270, a rack 260 coupled tojoining structure part 231, and a pinion element 276 coupled to knob 270and including a bore 273 to receive a shaft 215 extending from thesurface of indicator element 21 opposite the exposed face thereof.According to the illustrated embodiment, shaft 215 of indicator element21 extends through a slot 202 of joining structure part 232 and througha slot 203 of joining structure part 231 to mate with bore 273 of pinionelement 276; when knob 270 is rotated, pinion element 276 rotates aboutshaft 215 and travels along rack 260 thereby moving indicator element 21in the direction parallel to plane 2. FIG. 2B illustrates calibrationmarkings 275 located both on knob 270 and above rack 260 so that aposition of knob 270 with respect to rack 260 may be correlated by auser to a depth of the target beneath device 100 and located by device100, which depth may have been measured by device 100. According to analternate embodiment, rather than the illustrated rack-and-pinioninterface, slot 202 and/or slot 203 includes a series of detents, orrecesses, spaced apart along a length thereof and into which shaft 213of indicator element 21 may be positioned by sliding shaft 213, with orwithout knob 270, along the length.

Joining structure parts 231, 232, indicator element 21, and theadjustment mechanism components described above may all be formed, forexample, via injection molding, from a suitable plastic, for example,ABS, nylon, acetal resin, or polycarbonate, and then snap fittedtogether to assembly guide 20. Both device 100 and attached guide 20 maybe inserted into a transparent and flexible protective covering, forexample, similar to covering 180 shown in FIGS. 1A-B, for performing ascan and an associated needle insertion, since pointers 209, 210, 211 ofguide 20, similar to guide 10, can easily be viewed through thecovering, to guide the orientation of a needle to an indicated entrysite, and the adjustment mechanism of guide 20 may be manipulated bygrasping knob 270 from outside the covering. Alternately, joiningstructure parts 231, 232 of guide 20 may be snapped together arounddevice 100 which has already been inserted into the protective coveringso that guide is outside the covering during the scanning and needleinsertion.

FIG. 3A is a perspective view of a needle guide 30 attached to medicalscanning device 100, according to additional embodiments of the presentinvention; and FIG. 3B is a top perspective view of needle guide 30.FIGS. 3A-B illustrate a joining structure 33 of guide 30 including asidewall having portions 331, 332, 333 and 334 to form a receptacle 335for holding device 100; receptacle 335 includes a first opening 313,through which device 100 is inserted, and a second opening 315, throughwhich transducer surface 101 of device 100 is exposed for scanning, andjoining structure 33 includes a spring member 360, which may help toposition and to retain device 100 within receptacle 335. An operator mayposition device 100 within receptacle 335 such that transducer surface101 protrudes slightly from second opening 315, as shown, or such thattransducer surface 101 is approximately flush with a flange 340 ofjoining structure 33; flange 340 is shown extending outward from thejoining structure sidewall, approximately aligned with opening 315, andmay serve to maintain a constant orientation of device 100 whentransducer surface 101 is placed over an epidermis during scanning andneedle insertion.

FIGS. 3A-B further illustrate an indicator element 31 of guide 30including a pointer 310, formed by a groove in a side surface thereof;indicator element 31 is shown coupled to flange 340 of joining structure33 via a coupling 312, into which indicator element 31 is snap-fitted ata fixed angle with respect to joining structure 33; according to someembodiments coupling 312 allows indicator element to pivot, per arrow A,into various fixed positions, for example in 10 degree increments.According to the illustrated embodiment, a position of a terminal endP30 of pointer 310 is fixed in relation to joining structure 33, and anadjustment mechanism of guide 30 includes a knob 354 to move joiningstructure 33, with respect to device 100, in a direction parallel to aplane (like plane 2 shown in FIGS. 1A-B and FIG. 2A), which isapproximately tangent with an apex of transducer surface 101 andapproximately perpendicular to longitudinal axis 4 of device 100,thereby moving indicator element 31 with respect to device 100 in adirection parallel to the same plane. It should be noted that pointer310 may alternately be formed by an edge protruding from the sidesurface of indicator element 31 or just as the side surface itself.

FIG. 3B illustrates the adjusting mechanism of guide 30 including a knob354, located adjacent an external surface of sidewall portion 332, and ashaft 352 extending from knob 354 through sidewall portion 332 to aterminal end 305 thereof, which contacts inserted device 100 (device 100represented with a dashed line in FIG. 3B), and forces device 100against spring member 360. Knob 354 may be used to advance or retractterminal end 305 of shaft 352, per arrow B, causing a relative movementbetween device 100 and both joining structure 33 and indicator element31, so that indicator element 31 remains in a fixed location withrespect to joining structure 33 while being moved with respect to device100. Although spring member 360 is shown as a leaf spring, it should beappreciated that any type of spring member, which applies a resistiveforce against device sidewall 103 to hold device 100 in receptacle whileallowing movement of device 100 therein, may be incorporated byembodiments of the present invention.

Referring back to FIG. 3A, knob 354 is shown including calibration marks375 to be used in conjunction with an indicator 385, which is coupled tosidewall portion 332, in proximity to knob 354. With reference to FIGS.3A-B it should be appreciated that a threaded interface between shaft352 and sidewall portion 332 controls travel, per arrow B, of terminalend 305; the controlled travel of terminal end 305, which is effected byrotating knob 354, is calibrated to position device 100 with respect toindicator element 31, such that indicator marks 375, being aligned withindicator 385, each correspond to a different depth of a subcutaneoustarget, located by device 100, that a needle will pass through beingguided by pointer terminal end P30, which is located at a distance dfrom axis 4 of device 100, and according to the angular orientation ofpointer 310. According to some alternate embodiments, shaft 352 includesdetent notches interfacing with sidewall portion 332, rather thanthreads, and knob 354 is pushed rather than turned in order to adjustdistance d.

FIGS. 4A-B are schematics depicting an exemplary procedure that mayemploy embodiments of the present invention. FIG. 4A illustrates sacralnerves 45 of a patient 40 located adjacent to an anterior surface of thepatient's sacrum 43, which is the relatively large triangular bonesituated at the lower part of the vertebral column. FIG. 4A furtherillustrates access to nerves 45 being gained by a percutaneous needle400 inserted, from a posterior side of sacrum 43, through a foramen 51of sacrum 43 (typically, the third sacral foramen, or S3). Such accessis desired in order to provide electrical stimulation, orneuromodulation treatment, to sacral nerves 45, thereby influencing thebehavior of the patient's organs that sacral nerves 45 innervate, forexample, to treat urinary incontinence. FIG. 4B illustrates an implantedneuromodulation system including a stimulation device 460 coupled to anelongate medical electrical lead 410 via an extension lead 450; prior tocoupling with device 460, lead 410 has been inserted through sacralforamen 51, for example, via needle 400, and an electrode of lead 410has been coupled to underlying sacral nerve 45 in order to delivercontrolled electrical stimulation thereto from device 460.

With reference back to FIG. 4A, it may be appreciated that protuberancesof sacrum 43 can provide landmarks for determining an appropriate entrysite for needle 400, and knowledge of a typical curvature of sacrum 43,in relation to a contour of the exterior body surface, or epidermis ofpatient 40, surrounding the needle entry site, has helped to establishan approximately 60 degree angle of insertion for needle 400, whichallows needle 400 to pass through foramen 51 in order to contact nerves45, and which angle is known to those skilled in the art. Once properlyinserted, as illustrated in FIG. 4A, needle 400 provides a pathway,through a lumen thereof, by which lead 410 may be implanted as aninitial step in the implantation of the system shown in FIG. 4B.

Often times the needle insertion illustrated in FIG. 4A is accomplishedunder local anesthetic by probing with needle 400 and using tactilefeedback to find foramen 51. For a skilled and experience physician, orclinician, such an approach may be acceptable, but, with the advent ofnon-invasive medical scanning systems, for example, those includinghandheld ultrasound transducer probes, an approach that employs thesesystems, to provide more concrete feedback in guiding needle insertion,may be preferred in many instances.

FIG. 5A is a schematic depicting percutaneous needle access obtainedaccording to some methods of the present invention, wherein device 100and needle guide 30 are employed; and FIG. 5B is a reproduction of anexemplary ultrasound scan obtained by device 100 in locating sacralforamen 51. FIG. 5A illustrates transducer surface 101 of device 100placed over the epidermis of patient 40 and device 100 coupled via cord3 to a console 6; according to exemplary embodiments of the presentinvention, device 100 and console 6 make up an ultrasound machinewherein device 100 is an ultrasound transducer probe that sends andreceives sound waves, and console 6 includes a central processing unit,transducer pulse controls, a display screen 56 and a user interface 65,for example a key board and/or touch pad. According to the illustratedembodiment, a physician or clinician has placed transducer surface 101of device 100 over the epidermis of patient 40, which overlies sacrum43, and has located foramen 51 by moving transducer surface 101 alongsacrum 43 while scanning. Guide 30 may have been attached to deviceeither before or after scanning to locate foramen 51. Although notshown, those skilled in the art will appreciate that device 100 and,optionally, guide 30 too, if attached prior to scanning, will typicallybe placed within a protective covering, for example, like cover 180previously described, and that a conductive gel will be spread betweentransducer surface 101 and the covering to facilitate the scanningprocess. FIG. 5B shows an image 560, which may be generated by device100, once foramen 51 has been located by device 100, and displayed onscreen 56; image 560 was obtained with a 38 mm broadband linear arrayultrasound transducer probe of a MicroMaxx® system, available fromSonoSite, Inc., using a scanning frequency of 7.5 MHz.

With further reference to FIG. 5B, those skilled in the art willappreciate that a difference in reflection of ultrasound energy frombone and adjacent soft tissue creates the contrast between bone (shownblack in image 560) and soft tissue (shown gray in image 560) that helpsto identify the location of foramen 51. In addition to locating foramen51, device 100 in conjunction with image 560 may be used to determine adepth of the posterior opening of foramen 51; depths are shown by tickmarks along the right hand side of image 560, and a dashed white linehas been superimposed on the image to indicate an approximate depthbetween 1.5 and 2 cm of the posterior opening of foramen 51, as measuredby the ultrasound probe in this particular instance. The depth of theopening may vary from patient to patient depending upon a thickness ofsubcutaneous tissue overlying the sacrum for each patient. As previouslydescribed, indicator element 31 is moved with respect to device 100, inthe previously described parallel direction, into a position wherepointer 310 of indicator element 31 points to an appropriate needleentry site E51 that corresponds to the fixed angular orientation ofindicator element 31 (FIG. 5A). With reference back to FIG. 4A, thefixed angular orientation of indicator element 31 should beapproximately 60 degrees to assure passage of needle 400 through foramen51 to underlying nerves 45; however, it should be understood that needleguides of the present invention may be used for other applicationswherein other angular orientations are appropriate. It should be notedthat any of the previously described embodiments of needle guides, forexample, guides 10 and 20, may be employed for guiding needle 400.

Once foramen 51 has been located, a depth thereof measured, and, ifnecessary, guide 30 has been adjusted, needle 400 may be inserted at theentry site, and per the orientation indicated by indicator element 31.According to some methods of the present invention, the insertion ofneedle 400 may be visualized via ultrasound, for example, on displayscreen 56 (FIG. 5A); a metal shaft of needle 400 will be echogenic forultrasound visualization, and some embodiments of needle 400 may have aroughened surface known to enhance echogenic properties. Alternately, oradditionally, proper insertion of needle 400 may be verified viaelectrical testing. Turning now to FIG. 6A, which is a plan view ofpercutaneous access needle 400, needle 400 is shown including aconductive shaft 603 attached to a hub 604, wherein a tip 643 and aproximal portion 641 of shaft 603 are exposed for electrical contact,and a length 642 of shaft 603, between tip 643 and proximal portion 641is insulated. According to the illustrated embodiment, once needle 400is passed through foramen 51, a test stimulation may be applied atportion 641 in order to determine if tip 643 is contacting nerve 45; ifcontact with nerve 45 is made a motor response in the buttock area willbe observed. FIG. 6B is a perspective view of an alternate embodiment ofguide 30, denoted as guide 30′, which includes electrical contactfeatures to facilitate application of the test stimulation to needle400.

FIG. 6B illustrates indicator element 31 of guide 30′ including amounting feature 637 for an electrical contact clip 64, which is showncoupled via lead wire 670 to a test stimulator device 67; contact clip64, being mounted to guide 30′, as shown, may provide stability toinserted needle 400, being coupled to clip 64 during the stimulationtesting. According to the illustrated embodiment, mounting feature 637is formed by a post, which protrudes from an end of indicator element 31and about which clip 64 may be attached for mounting; if a protectivecovering is disposed about device 100 and guide 30′, clip 64 may stillbe mounted on feature 637 from outside the covering. Although not shown,it should be appreciated that a circuit for test stimulation must becompleted by grounding stimulator device 67; such grounding is typicallyaccomplished via a ground pad connected to the epidermis of the patient.However, FIG. 6B further illustrates a conductive surface 634, which iscoupled to flange 340 of guide 30′ and is electrically isolated frommounted contact clip 64, and which may be used to ground stimulatordevice 67. According to the illustrated embodiment, when guide 30′ isattached to device 100, and transducer surface 101 is placed over theepidermis for scanning, a ground wire (not shown) of stimulator device67 may be coupled to conductive surface 634 of guide 30′, which isgrounded to the epidermis, for example, via direct contact therewithand/or via an interface of conductive gel. Thus, guide 30′ includesuseful features facilitating handling of inserted needle 400 inconjunction with device 100 during electrical stimulation testing forverification of proper needle insertion. It should be noted thatalternate embodiments of guide 30′ need not include both mountingfeature 637 and conductive surface 634, but may include one or theother.

FIG. 7 is a flow chart outlining/summarizing various methods of thepresent invention, which have been discussed in greater detail above.FIG. 7 illustrates alternative pairs of initial steps: steps 71 and 72wherein a medical scanning device (i.e. device 100) is inserted into aprotective covering prior to attaching a needle guide (i.e. guide 10,20, or 30) thereto; and steps 701 and 702 wherein the needle guide isattached to the device and then the device and attached guide insertedinto the protective covering. FIG. 7 shows, following either of thesepair of initial steps, a step 73, wherein scanning is performed tolocate a target (i.e. foramen 51); however, it should be noted that step73 may be performed in between steps 71 and 72, according to analternate method, such that scanning is performed to locate the targetbefore the needle guide is attached to the device. After step 73, adepth of the located target is determined, per step 74, and then theguide is adjusted according to the depth, per step 75, so that a needle(i.e. needle 400) may be oriented and inserted into an entry site (i.e.E51) indicated by the adjusted needle guide, per step 76; of course, ifan initial position of an indicator element of the guide happens tocoincide with the determined depth of the target, adjustment of theguide, per step 75, is not necessary. According to some alternatemethods, step 76 immediately precedes step 73, wherein the depth of thelocated target is foreknown and the needle guide need not be adjusted;an embodiment of a fixed needle guide, that does not include anadjustment mechanism, was described in conjunction with FIG. 1C, andanother embodiment will be described below in conjunction with FIG. 8.FIG. 7 further illustrates optional steps 77 and 78 following insertionof the needle, per step 76: according to step 77, the needle isvisualized during insertion, and, according to step 78, electricaltesting is performed to verify proper insertion of the needle. It shouldbe noted that either of steps 77 and 78 may be included in a methodwithout the other being included.

Various embodiments of adjustable needle guides have been heretoforedescribed, along with one embodiment of a fixed needle guide; now,another embodiment of a fixed needle guide will be described inconjunction with FIG. 8. FIG. 8 is a schematic depicting a fixed needleguide 80, attached to medical scanning device 100, wherein plane 2 isapproximately tangent to the apex of transducer surface 101 andapproximately perpendicular to longitudinal axis 4 of device 100. FIG. 8illustrates guide 80 including a plate 81 and a joining structure 83,which reversibly attaches guide 80 to device 100 such that plate 81extends laterally from transducer surface 101 and external sidewall 103of device 100. FIG. 8 further illustrates plate 81 including pointers811, 812, 813, which extend over a length along an exposed surface ofplate 81; pointers 811, 812, 813 may be formed as grooves or protrudingsurfaces, or any other type of marking on the exposed surface of plate81. According to the illustrated embodiment, each of pointers 811, 812,813 extend at a fixed angle φ with respect to plane 2, and are spaceapart from one another in a direction approximately parallel with plane2; each of pointers 811, 812, 813 points to a needle entry site E1, E2,E3, respectively, each of which corresponds to a depth of a target TD1,TD2, TD3, respectively, and depending on which depth is measured for thetarget, the corresponding pointer is selected to guide insertion of apercutaneous needle per the corresponding insertion path shown withdashed lines. Each of pointers 811, 812, and 813 may include a visiblecalibration mark indicating the depth to which each correspond, or somekind of color coding identifying the corresponding depth. Although notshown, it may be appreciated that both device 100 and attached guide 80may be enclosed in a translucent protective covering, for example,similar to that shown in FIGS. 1A-B, for scanning and subsequent guidingof a percutaneous needle insertion according to the selected pointer,since pointers 811, 812, 813, may be visualized through the covering.

In the foregoing detailed description, the invention has been describedwith reference to specific embodiments. However, it may be appreciatedthat various modifications and changes can be made without departingfrom the scope of the invention as set forth in the appended claims.

1. A percutaneous needle guide for a medical scanning device, the deviceincluding a transducer surface to place over an epidermis of a body forscanning and an external sidewall extending away from the transducersurface, the needle guide comprising: a joining structure for reversiblyattaching the guide to the device; and a plate coupled to the joiningstructure and extending laterally from the transducer surface of thedevice and the external sidewall of the device, when the guide isattached to the device; wherein the plate includes a plurality ofpointers, each pointer of the plurality of pointers for pointing apercutaneous needle to a needle entry site on the epidermis withoutconstraining the needle, each pointer being formed in an exposed surfaceof the plate, and each pointer extending over a length along the exposedsurface at a fixed angle with respect to a plane that is approximatelytangent with an apex of the transducer surface of the device andapproximately perpendicular to a longitudinal axis of the device, whenthe guide is attached to the device.
 2. The needle guide of claim 1,wherein: each of the plurality of pointers spaced apart from one anotheralong the lateral extension of the plate; and the fixed angle of each ofthe plurality of pointers is the same.
 3. The needle guide of claim 1,further comprising an adjustment mechanism coupled to the joiningstructure for moving the plate, with respect to the device, in adirection approximately parallel to the plane, when the guide isattached to the device; wherein the adjustment mechanism moves the platewithout changing an angular orientation of any of the plurality ofpointers formed in the exposed surface thereof.
 4. A method for gainingpercutaneous access through a sacral foramen for stimulation of a sacralnerve, the method comprising: attaching a percutaneous needle guide to amedical scanning device such that an indicator element of the guide islaterally offset from a transducer surface of the device; placing thetransducer surface of the device over an epidermis of a body; moving thedevice over the epidermis, while scanning with the device, to locate thesacral foramen; orienting a percutaneous needle toward a needle entrysite on the epidermis, the needle entry site being indicated by apointer of the indicator element of the guide, and the needle beingoriented according to an entry angle depicted by the pointer; andinserting the oriented percutaneous needle into the entry site andthrough the sacral foramen; wherein the orienting and inserting of theneedle are performed without the needle being constrained by thepointer.
 5. The method of claim 4, further comprising inserting thedevice and the attached guide into a covering before moving the deviceover the epidermis.
 6. The method of claim 4, wherein the guide isattached to the device after moving the device to locate the sacralforamen.
 7. The method of claim 4, further comprising: determining adepth of the sacral foramen from a scan of the device located over thesacral foramen; and moving, with respect to the device, in a directionapproximately parallel to a plane that is approximately tangent with anapex of the transducer surface of the device and approximatelyperpendicular to a longitudinal axis of the device, the indicatorelement of the attached guide from a first position to a secondposition, the second position corresponding to the determined depth ofthe sacral foramen and the entry angle depicted by the pointer.
 8. Themethod of claim 7, wherein the device is held over the sacral foramenwhen the indicator element is moved.
 9. The method of claim 4, furthercomprising visualizing insertion of the needle via the device.
 10. Themethod of claim 4, further comprising coupling a stimulation source tothe needle for electrical testing.
 11. The method of claim 10, furthercomprising coupling the stimulation source to the guide for groundingvia an electrical coupling between the guide and the epidermis.
 12. Theneedle guide of claim 3, wherein the plurality of pointers have a commonterminal end, and the fixed angle of each of the plurality of pointersis different from one another.
 13. The needled guide of claim 12,wherein the adjustment mechanism is calibrated to correlate each of aplurality of positions, into which the common terminal end of theplurality of pointers is moved by the adjustment mechanism, with acorresponding subcutaneous depth beneath the device, when the transducersurface is placed over the epidermis for scanning, and when the guide isattached to the device.
 14. The needle guide of claim 13, wherein theadjustment mechanism includes calibration marks indicating the depthcorresponding to each of the plurality of positions.
 15. The method ofclaim 4, wherein the pointer of the indicator is one of a plurality ofpointers formed in an exposed surface of a plate of the indicator, eachof the plurality of pointers extending at a fixed angle with respect toa plane that is approximately tangent with an apex of the transducersurface of the device; and further comprising: determining a depth ofthe sacral foramen from a scan of the device located over the sacralforamen; and moving, with respect to the device, in a directionapproximately parallel to the plane that is approximately tangent withthe apex of the transducer surface and approximately perpendicular to alongitudinal axis of the device, the indicator element of the attachedguide from a first position to a second position, without changing anangular orientation of any of the plurality of pointers, the secondposition corresponding to the determined depth of the sacral foramen andthe entry angle depicted by the pointer.
 16. The method of claim 7,wherein: attaching the guide to the device comprises inserting thedevice into a receptacle of the guide, the receptacle being formed by asidewall of the joining structure such that the transducer surface ofthe inserted device is exposed for scanning through an opening in thesidewall of the joining structure, and a spring member of the guide,which is mounted against a portion of the joining structure, interfaceswith an external sidewall of the inserted device; and moving theindicator element from the first position to the second positioncomprises adjusting a knob of an adjustment mechanism of the guide tomove the joining structure of the guide with respect to the device,against a resistive force of the spring member, the adjustment mechanismbeing coupled to the joining structure and extending through thesidewall of the joining structure to contact the external sidewall ofthe inserted device, opposite the interface with the spring member.